Medical sensor

ABSTRACT

The present invention relates to a medical sensor ( 1 ) for measuring pulse, blood, tissue and/or skin parameters by means of electromagnetic waves in the transmission or reflection method. The sensor ( 1 ) has a strip- and/or band-shaped carrier part ( 2 ) which carries at least one transmitter element and at least one receiver element. In order that the sensor ( 1 ) can be used on a patient more than once and is sufficiently secured against relative movements with respect to a body part, the carrier part ( 2 ), on an inner side ( 9 ) provided to make contact with the body part, has at least two adhesive bodies ( 25, 26 ) which are spaced apart from one another and during measurement adhere to the body part, while the rest of the inner side ( 9 ) is designed to be essentially non-adhesive with respect to the body part.

The present invention relates to a medical sensor for measuring pulse,blood, tissue and/or skin parameters by means of electromagnetic wavesin the transmission or reflection method, having the features of theprecharacterizing clause of claim 1.

During an operation or during a stay in intensive care, it may beexpedient to check and monitor, inter alia, the lung function,metabolism and heart rate of a patient. This may be carried out, forexample, by measuring the oxygen saturation and the pulse rate. Forthis, sensors of the type mentioned above are used, by means of which ameasurement, derived from the pulse, of the arterial oxygen saturationcan be carried out using an optoelectronic transmission measurement orreflection measurement. Such a sensor usually comprises at least onetransmitter, for example a light-emitting diode LED which can emitinfrared light and an LED which can emit red light, and also at leastone receiver, usually a photodiode. Furthermore, such a sensor comprisesa carrier assembly which positions the transmitter and receiver in thedesired manner on a body part of the patient, for example on the finger,toe, hand or foot.

With sensors, a distinction is made between single-use sensors, whichcan be used only once, semi-reusable sensors, in which a throwaway partcan be replaced after each use, and reusable sensors, which can be usedto carry out a number of measurements. With reusable sensors, adistinction can also be made between those which can be used fordifferent patients one after the other and those which can be used anumber of times but only for the same patient.

EP 0 127 947 B1 and U.S. Pat. No. 5,891,026 disclose sensors of theabovementioned type which in each case have a strip- or band-shapedcarrier part which for the respective measurement is wound around thefinger, toe, hand or foot.

In the case of the sensor disclosed in U.S. Pat. No. 5,891,026, thesensor is attached to the respective body part by means of a Velcrofastening (hook and loop fastening). An inner side of the carrier part,which bears against the respective body part, is in this case designedto be completely non-adhesive. By virtue of this design, this sensor canbe used a number of times on the same patient. With this sensor, thereis no direct fixing of the carrier part to the respective body part, sothat in the event of voluntary or involuntary movements of the patientthere is a risk that the carrier part will slip in relation to the bodypart and the measurements will be impaired as a result.

In the case of the sensor disclosed in EP 0 127 947 B1, an inner side ofthe carrier part, which bears against the respective body part, isdesigned in its entirety as an adhesive surface which fixes the carrierpart directly to the body part. This sensor, which is also referred toas an adhesive sensor, is securely fixed to the body part for therespective measurement. However, such an adhesive sensor can be usedonly once. Furthermore, during removal of such an adhesive sensor fromthe respective body part, there is the risk of damage to the skin, inparticular in the case of neonatal or geriatric patients.

U.S. Pat. No. 3,810,460 and U.S. Pat. No. 4,685,464 disclose sensorswhich are designed as clip sensors, the carrier part of which in eachcase has two legs mounted such that they can pivot in relation to oneanother about an axis of pivoting. These clip legs are prestressed inthe closing direction by means of an appropriate spring, so that theclip sensor can be clipped, for example, to a finger in a self-retainingmanner. Such sensors are relatively expensive to produce, so that theycan be provided only as reusable sensors.

DE 37 03 458 C2 and U.S. Pat. No. 4,109,643 disclose further sensorswhich are designed as cuff sensors, the carrier part of which forms asleeve which can be pushed onto the finger or toe. Such sleeve sensorsare also relatively expensive to produce, so that they can only beprovided as reusable sensors.

It is an object of the present invention to specify an improvedembodiment for a medical sensor of the type mentioned above, which inparticular allows multiple use on the same patient and is held on therespective body part in an improved manner.

This object is achieved according to the invention by the subject matterof the independent claim. Advantageous embodiments form the subjectmatter of the dependent claims.

The invention is based on the general concept of forming two or morelocally defined adhesive zones on the inner side of the carrier part,which adhesive zones have increased friction and/or adhesion in relationto the body part compared with the rest of the inner side of the carrierpart. In this context, the invention makes use of the knowledge that,for adequate attachment of the carrier part to the respective body part,it is sufficient to adhere the carrier part to more locations on thebody part, said locations being spaced apart from one another. Since,according to the invention, it is not the entire inner side of thecarrier part that is designed to be adhesive, the risk of damage to theskin when removing the sensor is reduced, even in the case of patientswith sensitive skin. Furthermore, the sensor according to the inventiondoes not become unusable upon removal from the body part, so that it canbe used a number of times on the same patient.

In a further embodiment, two adhesive bodies for forming two adhesivezones may be provided, where a first adhesive body covers the at leastone transmitter element while the second adhesive body covers the atleast one receiver element. The two adhesive bodies are designed to bepermeable to the electromagnetic waves used for measurement. Thisdevelopment is based on the knowledge that for the quality of themeasurements it is of primary importance that transmitter and receiverdo not change their relative position with respect to the body part,whereas relative movements of other components of the sensor have littleor no influence on the measurements. Accordingly, this embodimentcomprises only two adhesive bodies, one of which is positioned in theregion of the transmitter and the other of which is positioned in theregion of the receiver. In a particular embodiment, the at least onetransmitter element may be arranged inside the carrier part, with atransmitter opening being made in the carrier part, through whichtransmitter opening the at least one transmitter element emits wavesduring measurement, the first adhesive body being arranged in thistransmitter opening. In addition or as an alternative, the at least onereceiver element may be arranged in the carrier part, with a receiveropening being made in the carrier part, through which receiver openingthe at least one receiver element receives waves during measurement, thesecond adhesive body being arranged in this receiver opening. By virtueof this construction, the inner side of the carrier part can be designedto be particularly skin-friendly, so that the attached sensor inparticular does not generate any uncomfortable pressure points.Furthermore, by virtue of this construction, the handling of the sensoris simplified, since its carrier part can be attached to the respectivebody part in a simpler manner.

The adhesive bodies may consist for example of a gel-like adhesivecompound. As an alternative or in addition, the adhesive bodies mayconsist of an adhesive that is not hardened and does not harden duringthe service life of the sensor—if used correctly. By virtue of theseconfigurations, it is possible to achieve for the adhesive bodies, in aparticularly simple manner, an adhesive action which on the one handensures sufficiently secure fixing of the carrier part to the body partand on the other hand can be regularly removed from the respective bodypart without any damage to the skin.

Other important features and advantages of the invention emerge from thesubclaims, the drawings and the associated description of the figures,which is given with reference to the drawings.

It will be understood that the features mentioned above and those thatare yet to be mentioned below can be used not only in the combinationindicated in each case but also in other combinations or on their own,without departing from the scope of the present invention.

The invention will be further described with reference to examples ofembodiments shown in the drawings to which, however, the invention isnot restricted. In the drawings, the same reference numerals refer toidentical or functionally identical or similar components.

FIG. 1 schematically shows a perspective view of the individual parts ofa sensor according to the invention.

FIG. 2 schematically shows a perspective view of the sensor according tothe invention in the assembled state.

As shown in FIG. 1, a medical sensor 1 according to the inventioncomprises a carrier part 2 which is designed in the shape of a strip orband. The sensor 1 is used to measure pulse, blood, tissue or skinparameters, where the sensor 1 operates using electromagnetic waves andin this case uses a transmission or reflection method. For this purpose,the carrier part 2 carries a transmitter unit 3, which comprises atleast one transmitter element. The transmitter unit 3 usually comprisesan LED that emits red light and an LED that emits infrared light.Furthermore, the carrier part 2 carries a receiver unit 4, whichcomprises at least one receiver element, preferably a photodiode. Thetransmitter unit 3 or its transmitter element and the receiver unit 4 orits receiver element are connected to a plug 6 via cables 5, the cables5 being gathered together in a composite cable 7 outside the carrierpart 2.

The carrier part 2 is constructed in a multilayer fashion. In order tobe able to better illustrate the individual layers, these are shown onan overproportionally enlarged scale in the direction of their thicknessin FIGS. 1 and 2.

As shown in FIG. 1, the carrier part 2 comprises an inner half 2 a andan outer half 2 b, which may be produced independently of one another.The inner half 2 a in this case consists of a first textile layer 8which forms an inner side 9 of the carrier part 2. This inner side 9,during use of the sensor 1, is applied to a body part of a patient, inparticular to a finger, a toe or, in small patients, a foot or a hand.The first textile layer 8 consists, for example, of velour and isdesigned such that it essentially does not adhere to the body part, thatis to say to human skin and hairs.

On the side facing away from the inner side 9, the first textile layer 8is connected, in particular adhesively or thermally bonded, to a firstlayer of foamed material 10. The first layer of foamed material 10consists, for example, of PE and is elastically compressible. In theembodiment shown here, a first adhesive film 11 is attached, inparticular adhesively or thermally bonded, to the first layer of foamedmaterial 10 on a side facing away from the inner side 9. The firstadhesive film 11 has an adhesive coating on its side facing away fromthe inner side 9. Once the inner half 2 a has been finished, thisadhesive coating is covered with a peelable protective film, which isonly peeled off for the purpose of assembling the sensor 1. In FIG. 1,this protective film has already been peeled off. The inner half 2 a andits components, that is to say the first textile layer 8, the firstlayer of foamed material 10 and—where present—the first adhesive film11, comprise a transmitter opening 12 and a receiver opening 13. Thetransmitter opening 12 and the receiver opening 13 are in each casearranged approximately on a longitudinal center line 14 of the carrierpart 2 and are spaced apart from one another in the longitudinaldirection of the carrier part 2.

The outer half 2 b consists of a similar multilayer construction andcomprises an outer side 15 of the carrier part 2, said outer side 15facing away from the inner side 9 and being formed by a second textilelayer 16. The second textile layer 16 may also consist essentially of askin-friendly material, such as velour for example. On its side facingaway from the outer side 15, the second textile layer 16 has a secondlayer of foamed material 17, which likewise consists of an elasticallycompressible foamed material, for example PE. Optionally, the secondlayer of foamed material 17 may have, on its side facing away from theouter side 15, a second adhesive film 18 which on its side facing awayfrom the outer side 15 has an adhesive coating. The connections betweenthe individual layers may also in this case be realized by adhesivelybonded connections or thermally bonded connections. After production ofthe outer half 2 b, the adhesive coating of the adhesive film 18 isexpediently covered with an appropriate protective film which can bepeeled off for assembly purposes, as in FIG. 1.

For assembly of the sensor 1, the transmitter unit 3, the receiver unit4 and the cables 5 and 7 are then positioned. In order to obtain fixingof the composite cable 7 to the carrier part 2 with good tensilestrength, a retaining plate 19 may be provided which is fitted to theouter part 2 b and is fixedly attached to the end section 21 of thecomposite cable 7 remote from the plug 6. Adhesively bonded connectionsare also preferred here for attachment purposes. If the second adhesivefilm 18 is provided, the retaining plate 19 can simply be placed on thesecond adhesive film 18 at the appropriate location. The retaining plate19 may also be provided with an adhesive layer which makes it possibleto fix the end section 21 of the composite cable 7 to the retainingplate 19. The retaining plate 19 expediently has two tabs 28 which foldaround the end section 21 for better fixing.

In order to further improve the fixing of the cables 5 and of thecomposite cable 7 to the carrier part 2, a projection 20 which sticksout to the side is formed on the carrier part 2, which projection 20 inthis case likewise consists of an inner half 20 a and an outer half 20b. The projection halves 20 a and 20 b are integrally formed on thecarrier inner half 2 a and on the carrier outer half 2 b or on thecomponents thereof. During assembly of the halves 2 a, 2 b of thecarrier part 2, the end section 21 of the composite cable 7 with thetabs 28 of the retaining plate 19 is arranged between the halves 20 a,20 b of the projection 20 and there adhesively and/or thermally bondedto the carrier part 2. As a result, effective strain relief of theoptoelectronic components 3, 4 is achieved.

In the preferred embodiment shown here, the carrier part 2 is moreoverequipped with a Velcro fastening 22, which has a hook element 23 havinghooks and a loop element 24 having loops. The loop element 24 is in thiscase formed by an appropriate configuration of the outer side 15 of thecarrier part 2, that is to say that an upper side of the second textilelayer 16, which forms the outer side 15 of the carrier part 2, serves asa loop element 24 for the Velcro fastening 22. Such a Velcro fastening22 may also be referred to as a hook and loop fastening.

In the embodiment shown here, the hook element 23 is designed as atongue which upon assembly of the sensor 1 is arranged at an end sectionbetween the halves 2 a, 2 b of the carrier part 2. After assembly of thesensor 1, the hook element 23 is thus arranged at one end between thelayers of foamed material 10, 17 or between the adhesive films 11, 18.As shown in FIG. 2, after assembly of the sensor 1, the hook element 22projects in the longitudinal direction of the carrier part 2, beyond thetextile layers 8, 16 thereof.

As shown in FIGS. 1 and 2, the sensor 1 according to the invention, onthe inner side 9 of the carrier part 2, has at least two adhesive bodies25, 26. In the preferred embodiment shown here, precisely two suchadhesive bodies are provided, and these will be referred to below as thefirst adhesive body 25 and the second adhesive body 26. The adhesivebodies 25, 26 are spaced apart from one another and thereby form twolocally defined adhesive zones within the inner side 9 of the carrierpart 2, which inner side 9 is designed to be non-adhesive per se. Theadhesive bodies 25, 26 are in this case dimensioned and positioned suchthat in the assembled state the first adhesive body 25 covers thetransmitter unit 3 while the second adhesive body 26 covers the receiverunit 4. In order not to impair the operability of the optoelectroniccomponents of the transmitter unit 3 and of the receiver unit 4, theadhesive bodies 25, 26 are made of a material which is permeable to theelectromagnetic waves that are emitted by the transmitter elements ofthe transmitter unit 3.

The adhesive bodies 25, 26 consist, for example, of a gel-like adhesive.This adhesive may be designed, for example, such that it is notcompletely hardened when it forms the adhesive bodies 25, 26 and suchthat it also does not harden during the entire predetermined servicelife of the sensor 1 provided that the sensor 1 is not exposed tounacceptable environmental conditions. In this way, the sensor 1 can beused on the same patient almost as often as desired. Thispatient-related reusability of the sensor 1 is aided by the Velcrofastening 22, which can likewise be opened and closed almost as often asdesired.

During application of the sensor 1, the carrier part 2 thereof is woundaround the respective body part of the patient. If the sensor 1 operatesin accordance with the transmission method, the carrier part 2 isattached to the body part such that transmitter unit 3 and receiver unit4 lie opposite one another on opposite sides of the body part. Theadhesive bodies 25, 26 then come to rest on the body part and by virtueof their adhesion at the measurement location produce adequate fixing ofthe carrier part 2 to the body part.

In order to be able to carry out optimal measurement of the pulse rate,it is desired that the carrier part 2 bears against the body part with aslight pressure. In the case of the sensor 1 according to the invention,the carrier part 2 is designed to be elastically compressible in thedirection of its thickness. This is achieved in this case by thecorrespondingly compressible layers of foamed material 10, 17. Thecompressibility of the carrier part 2 is designed such that the carrierpart 2, during application to the respective body part, can becompressed to the extent that resulting restoring forces press the innerside 9 of the carrier part 2 against the body part. Upon winding aroundthe respective body part, a prestressed bearing of the carrier part 2 onthe body part is thus generated, which prestressing can be fixed withthe aid of the Velcro fastening 22.

In order to be able to wind the multilayer carrier part 2 in aparticularly simple manner such that transmitter element 3 and receiverelement 4 can be positioned on opposite sides of the body part, inaccordance with the embodiment shown here the carrier part 2 may havelateral notches 27 that lie opposite one another and are arranged in thecenter, with respect to the longitudinal direction of the carrier part2, between transmitter element 3 and receiver element 4. The notches 27are V-shaped and run inward to form a point. The notches 27 may beformed during production of the halves 2 a, 2 b of the carrier part 2,so that the carrier part halves 2 a, 2 b or their layers 8, 10, 11 and16, 17, 18 are accordingly provided with the notches 27.

As can be seen particularly clearly in FIG. 2, the first adhesive body25 is preferably inserted in the transmitter opening 12, with the firstadhesive body 25 expediently completely filling the transmitter opening12. In this embodiment, in a corresponding manner, the second adhesivebody 26 is inserted in the receiver opening 13 and expedientlydimensioned such that it completely fills the receiver opening 13. Theadhesive bodies 25, 26 may be designed such that they adhere to thetransmitter element 3 and to the receiver element 4, respectively. Theadhesive bodies 25, 26 may consist, for example, of a gel-like adhesivecompound which is poured into the openings 12, 13 during production ofthe sensor 1. This adhesive compound then solidifies or hardens to adefined extent, with the adhesive compound being designed such that, onthe inner side 9 of the carrier part 2, it has a surface which adheresat least to human skin. In order to be able to transport the finishedsensor 1, it is expedient to apply a peelable protective film (notshown) to the inner side 9 of the carrier part 2 also in the region ofthe adhesive bodies 25, 26. This protective film may then be removeddirectly before use of the sensor 1.

On account of the arrangement of the optoelectronic components 3, 4 ofthe sensor 1 between the carrier part halves 2 a, 2 b, followingassembly of the sensor 1 the transmitter unit 3 and the receiver unit 4are housed in a protected manner inside the carrier part 2.

LIST OF REFERENCES

-   -   1 sensor    -   2 carrier part    -   3 transmitter unit    -   4 receiver unit    -   5 cable    -   6 plug    -   7 composite cable    -   8 first textile layer    -   9 inner side of 2    -   10 first layer of foamed material    -   11 first adhesive film    -   12 receiver opening    -   13 transmitter opening    -   14 longitudinal center line of 2    -   15 outer side of 2    -   16 second textile layer    -   17 second layer of foamed material    -   18 second adhesive film    -   19 retaining plate    -   20 projection on 2    -   21 end section of 7    -   22 Velcro fastening    -   23 hook element of 22    -   24 loop element of 22    -   25 first adhesive body    -   26 second adhesive body    -   27 notch    -   28 tab

1. A medical sensor for measuring pulse, blood, tissue and/or skinparameters by means of electromagnetic waves in the transmission orreflection method, having a strip- and/or band-shaped carrier part whichcarries at least one transmitter element and at least one receiverelement, wherein the carrier part, an inner side provided to makecontact with a body part of a patient, has at least two adhesive bodieswhich are spaced apart from one another and during measurement adhere tothe body part, where the rest of the inner side is designed to beessentially non-adhesive with respect to the body part.
 2. A sensor asclaimed in claim 1, wherein two adhesive bodies are provided, the firstadhesive body covers the at least one transmitter element, the secondadhesive body covers the at least one receiver element, the two adhesivebodies are permeable to the waves emitted by the at least onetransmitter element.
 3. A sensor as claimed in claim 2, wherein the atleast one transmitter element is arranged in the carrier part, with atransmitter opening being made in the carrier part, through whichtransmitter opening the at least one transmitter element emits wavesduring measurement, the first adhesive body being arranged in thetransmitter opening and/or the at least one receiver element is arrangedin the carrier part, with a receiver opening being made in the carrierpart, through which receiver opening the at least one receiver elementreceives waves during measurement, the second adhesive body beingarranged in the receiver opening.
 4. A sensor as claimed in claim 3,wherein the first adhesive body adheres to the at least one transmitterelement and/or the second adhesive body adheres to the at least onereceiver element.
 5. A sensor as claimed in claim 3, the first adhesivebody completely fills the transmitter opening and/or the second adhesivebody completely fills the receiver opening.
 6. A sensor as claimed inclaim 1, wherein the adhesive bodies consist of a gel-like adhesivecompound.
 7. A sensor as claimed in claim 1, wherein the adhesive bodiesconsist of an adhesive that is not hardened and does not harden duringthe service life of the sensor.
 8. A sensor as claimed in claim 1,wherein the carrier part is designed to be elastically compressible inthe direction of its thickness, such that the carrier part can becompressed at the time of application to the body part, such thatrestoring forces press the inner side of the carrier part against thebody part.
 9. A sensor as claimed in claim 1, wherein the carrier parthas a multilayer structure and, between two textile layers, one of whichforms the inner side of the carrier part and the other of which forms anouter side of the carrier part, has at least one layer of foamedmaterial that can be elastically compressed in the direction of thethickness.
 10. A sensor as claimed in claim 1, wherein the carrier parthas a first textile layer that forms the inner side of the carrier part,on which there is arranged a first layer of foamed material that can beelastically compressed in the direction of the thickness, on which thereis arranged a second layer of foamed material that can be elasticallycompressed in the direction of the thickness, on which there is arrangeda second textile layer that forms an outer side of the carrier part,where the at least one transmitter element and the at least one receiverelement are arranged between the layers of foamed material, where thefirst textile layer and the first layer of foamed material have atransmitter opening and a receiver opening through which the at leastone transmitter element emits waves during transmission and the at leastone receiver element receives waves.
 11. A sensor as claimed in claim10, characterized in that the at least one transmitter element and theat least one receiver element are arranged between a first adhesive filmand a second adhesive film, in that the adhesive films are arrangedbetween the layers of foamed material, in that the first adhesive filmhas a transmitter opening and a receiver opening.
 12. A sensor asclaimed in claim 9, wherein the layers of the multilayer carrier partare adhesively and/or thermally bonded to one another.
 13. A sensor asclaimed in claim 1, wherein the carrier part has a hook and loopfastening element comprising a hook element having hooks and a loopelement having loops.
 14. A sensor as claimed in claim 13, wherein thehook element is designed as a tongue which at one end is arrangedbetween the layers of foamed material or between the adhesive films andat the other end projects beyond the layers of foamed material.
 15. Asensor as claimed in claim 13, wherein the loop element is formed by anupper side of the second textile layer which forms the outer side of thecarrier part.
 16. A sensor as claimed in claim 1, wherein the at leastone transmitter element and the at least one receiver element arearranged on the carrier part on a longitudinal center line of thecarrier part and spaced apart from one another in the longitudinaldirection of the carrier part and wherein the carrier part has twolateral notches that lie opposite one another in the center, withrespect to its longitudinal direction, between the at least onetransmitter element and the at least one receiver element.
 17. A sensoras claimed in claim 1, wherein a projection which sticks out to the sideis formed on the carrier part, to which projection cables are attachedwhich lead to the at least one transmitter element and to the at leastone receiver element.
 18. A medical sensor comprising: a carrier part; areceiver located on a portion of said carrier part; a transmitterlocated on a portion of said carrier part; at least two adhesive bodies,wherein one adhesive body covers the receiver and another adhesive bodycovers the transmitter, wherein the receiver and the transmitter arespaced apart from one another.
 19. The medical sensor of claim 18,wherein said at least two adhesive bodies are comprised of a gel-likeadhesive material.